Estimation of evapotranspiration from a field of linseed in central Italy

A study was carried out in central Italy into the evapotranspiration from l inseed (Linum usitatissimum L.). In particular, the objectives were to (a) evaluate the accuracy of daily evapotranspiration estimates from partially incomplete Bowen ratio data; (b) measure seasonal evapotranspiration from l inseed; (c) test the FAO 56 method for estimating crop coefficients for lin seed and (d) calculate the surface resistance of the crop as a function of soil water status. The study was carried out on a crop of linseed growing i n a 1.1 ha field near Viterbo using Bowen ratio apparatus. Soil water conte nt and green area index were also monitored. It was found that (1) daily ev apotranspiration could be estimated from partially incomplete Bowen ratio d ata on a continuous basis throughout the growing season; (2) the linseed cr op lost 240 mm over the 100-day growing season; (3) measured crop coefficie nts agreed with those obtained using the FAO 56 methodology; (4) surface re sistance could be expressed as a function of green area index and soil wate r deficit seemed to have an indirect effect by hastening leaf senescence. ( C) 2000 Published by Elsevier Science B.V.